Sperm DNA Fragmentation Index (DFI)

When high

Read your lab's own threshold first. Methods differ and their cutoffs are not interchangeable. Halosperm and SCSA commonly treat above 30% as clinically significant, while some labs flag from 15%. Below roughly 15% is generally considered good, 15 to 30% is a grey zone worth acting on if you are trying to conceive, and above 30% is where the evidence for reduced pregnancy rates and increased miscarriage is strongest.

Timing matters more than almost anything else here:

• Shorten abstinence. Two to three days is conventional, but 1 to 2 days consistently lowers fragmentation, because sperm accumulate oxidative damage while stored in the epididymis. If you are producing a sample for testing or for IVF, a shorter abstinence usually gives a better result.
• Allow a full cycle before retesting. Spermatogenesis takes about 74 days plus epididymal transit. Retest at 3 months, not sooner, or you are measuring sperm that were already made before you changed anything.

Address the common drivers:

• Heat. Saunas, hot baths, heated seats, laptops on the lap, and prolonged cycling all raise scrotal temperature. This is one of the few genuinely reversible causes.
• Varicocele. The single most common correctable cause of high fragmentation. Worth a scrotal ultrasound if fragmentation is high and unexplained, since repair can meaningfully lower it.
• Smoking, vaping and heavy alcohol. All raise oxidative stress directly.
• Infection and inflammation. Check for genital tract infection if there are symptoms or raised leukocytes on the semen analysis.
• Body fat and metabolic health. Obesity raises fragmentation through oxidative and hormonal routes. See HbA1c.
• Age. Fragmentation rises with age independent of everything else, which is context rather than something to fix.

Supplements with reasonable evidence:

• CoQ10 200-300mg/day, the best supported of the antioxidants here
• Vitamin C 500-1000mg/day and Vitamin E 400 IU/day, often studied together
• Zinc 25-50mg/day and Selenium 100-200mcg/day
• L-carnitine 2-3g/day
• Give any of these a full 3 months before judging them. Do not megadose antioxidants indefinitely: excessive antioxidant load has itself been associated with sperm chromatin decondensation.

On-cycle and post-cycle context:

• If you are on suppressive compounds and planning to conceive, fragmentation should be assessed after recovery, not during. See Sperm Concentration and Total Motility for the wider recovery picture, and HCG for maintaining intratesticular testosterone.
• A normal count and motility post-cycle does not tell you fragmentation has recovered. That is the entire reason this test exists.

When it changes the plan:

• Persistently high fragmentation with otherwise normal parameters is a recognised reason to consider ICSI over IUI, and in selected cases testicular sperm (which is less fragmented than ejaculated sperm). That is a conversation for a fertility specialist, not a supplement stack.

References:

• Evenson, D. P., & Wixon, R. (2006). Meta-analysis of sperm DNA fragmentation using the sperm chromatin structure assay. Reproductive BioMedicine Online, 12(4), 466-472. DOI: 10.1016/s1472-6483(10)62000-7
• Agarwal, A., Majzoub, A., Esteves, S. C., et al. (2016). Clinical utility of sperm DNA fragmentation testing: practice recommendations based on clinical scenarios. Translational Andrology and Urology, 5(6), 935-950. DOI: 10.21037/tau.2016.10.03
• Ribas-Maynou, J., Yeste, M., Becerra-Tomas, N., et al. (2021). Clinical implications of sperm DNA damage in IVF and ICSI: updated systematic review and meta-analysis. Biological Reviews, 96(4), 1284-1300. DOI: 10.1111/brv.12700